To determine the value of ÄG°f(AgI2–(aq)), a researcher measured the concentrations at equilibrium to be: [I3–]eq = 4.07 M and [I2]eq = [AgI2–]eq = 0.686 M at 298 K.
2 Ag(s) + 2 I3–(aq) <------> 2 AgI2–(aq) + I2(aq)
ÄH°f(kJ/mole)/S°(J/k mole/ÄG°f at 298 K (kJ/mole)
Ag(s) 0 / 42.55 / 0
I3–(aq) –51.5 / 293.3 / –51.4
I2(aq) 22.6 / 137.2 / 16.40
What is the value of ÄG°f(AgI2–(aq)) in kJ?
To determine the value of ΔG°f (AgI2–(aq)), we can use the relationship:
ΔG°f = ΔH°f - TΔS°
where ΔH°f is the standard enthalpy change, ΔS° is the standard entropy change, and T is the temperature in Kelvin.
Given information:
ΔH°f(AgI2–(aq)) = 22.6 kJ/mol
ΔS°(AgI2–(aq)) = 137.2 J/(mol·K)
T = 298 K
First, we need to convert the units of ΔS° from J/(mol·K) to kJ/(mol·K) by dividing by 1000:
ΔS°(AgI2–(aq)) = 137.2 J/(mol·K) / 1000 = 0.1372 kJ/(mol·K)
Now, we can calculate ΔG°f(AgI2–(aq)) using the formula mentioned earlier:
ΔG°f(AgI2–(aq)) = ΔH°f(AgI2–(aq)) - TΔS°(AgI2–(aq))
ΔG°f(AgI2–(aq)) = 22.6 kJ/mol - (298 K × 0.1372 kJ/(mol·K))
ΔG°f(AgI2–(aq)) = 22.6 kJ/mol - 40.8356 kJ/mol
ΔG°f(AgI2–(aq)) ≈ -18.2356 kJ/mol
Therefore, the value of ΔG°f(AgI2–(aq)) is approximately -18.2356 kJ/mol.